ADS Application Notes. The Components Characterization Using ADS

Transcription

1 ADS Application Notes Wireless ommunication aboratory Department of Electrical and Electronic Engineering Hong Kong University of Science and Technology The omponents haracterization Using ADS

2 Introduction This application note describes the design procedure of developing accurate models for different component behavior using agilent s ADS. In the following part of this note, I will show the design procedures step by step. Design procedures 1. SMA model In this design, the SMA will be modeled as a phase shift plus an inductor and a capacitor. The phase shift will be modeled by an ideal transmission line. The category for select ideal transmission line is given below. Icon for ideal transmission line Symbol for ideal transmission line We can choose the electrical length for the transmission line. And after that we need to choose the lumped element for completing the model for the SMA. The icon for the lumped element is given below:

3 ategory for lumped components The final schematic for modeling the performance of SMA is shown below: Symbol for lumped components, resistor, capacitor, inductor 1 Ind=1.55 Res=1.43 Ph= ap=0.091 E=Ph F=4.5 GHz 1 =ap pf 2 =ap pf T3 E=Ph F=4.5 GHz From it we can see that we need to use the microstrip line to connect the two SMA. So the category for defining microstrip line is given below:

4 Icon for microstrip transmission line ious types of microstrip transitions Icon for defining properties of microstrip line We need to tune the value of the inductor and capacitor and the length of the ideal transmission line to fit the measured S-parameters including the magnitude and phase. 2. Via model We will not mention the theory of the vias. In a word, we will model the via as a inductor with a shunt parasitic capacitor. The schematic for the via model is shown below: 1 Ind=0.79 Res=0.01 ap=2 E=-11 F=1.5 GHz 1 =0.11 pf 2 =Ind nh R=Res Ohm 2 =ap pf

5 We will use the tuning function in the ADS to do the fitting. First we need to define the variables to be tuned. The icons are shown below: Symbols for the variables Button for defining the variables After simulation click the symbols for the variables in the schematic, pressing shift, then click the button for the tuning to start the tuning of the circuit. The button for tuning is given below: Button for tuning A tuning window will be prompted and is similar to the window below: Button for tuning

6 3. Resistor, capacitor and inductor 1 Ind=5 Res=0.212 E=-11 F=1.5 GHz 1 =0.11 pf R R1 2 R=Res Ohm =22 pf 2 =Ind nh R= 3 =0.79 nh R=0.01 Ohm 3 =2 pf Schematic for modeling the capacitor 1 Res=0.51 ap=1.126 E=-11 F=1.5 GHz 1 =0.11 pf 2 =12 nh R= R R1 R=Res Ohm 2 =ap pf 3 =0.79 nh R=0.01 Ohm 3 =2 pf Schematic for modeling the inductor

7 1 Ind=2.436 ap=0.855 E=-11 F=1.5 GHz 1 =0.11 pf 2 =Ind nh R= R R1 R=62 Ohm 2 =ap pf 3 =0.79 nh R=0.01 Ohm 3 =2 pf Schematic for modeling the resistor 4. Results The results are something similar to the figure shown below: db(s5_r..s(1,1)) db(s(1,1)) phase(s5_r..s(1,1)) phase(s(1,1)) freq, GHz S(1,1) Magnitude plot of Resistor freq, GHz S(1,1) Phase plot of Resistor We need to fit both the magnitude and the phase. onclusion In this note we show how to model the behavior of different components using ADS. All the necessary steps including the setting about tuning are given in this note. We can do the

8 parameters tuning easily with the help of ADS. It is very useful to do the modeling in modern design technique. And the agilent s ADS is powerful to do the circuit modeling.